High voltage insulating column with potential distribution rings



3,470,308 SWITH N M U L 0 c G mm T HA Sept. 30, 1969 J, M

- HIGH VOLTAGE INSUL POTENTIAL DISTR Filed May IBUTION RING 10. 196'? Fi .4 Fig.2 Fig.3

United States Patent Int. Cl. H01b 17/48 U.S. Cl. 174-141 9 Claims ABSTRACT OF THE DISCLOSURE A high voltage insulating column having means to protect against surge voltages, said means comprising one or more intermediate potential distribution rings of lesser diameter below a large diameter potential distribution n'ng carried by the column head element.

Potential distribution rings have been in use for quite some time. For example, such rings were used in the case of the surge diverter, lightning protector in order to distribute the voltage of 50 periods outside theinsulating sheath in a manner corresponding to the distribution of the voltage prevailing in the arrester column contained in the sheath. The potential distribution desired in this case has nothing to do with the improvement of the resistance of an insulating support to the shock wave, and the information derived from this cannot simply be transferred from one case to the next.

It has also been suggested that sets of rings, equipped with arresters, intended to remove the surface of the insulator as much as possible from an insulator arc-over, be so adapted that they can be used on bushing insulators or insulator support columns. This application likewise has nothing to do with the improvement of resistance to the shock wave which is the object of the device involved in this invention.

It is possiblein high voltage grids, especally in excess of 245 kv.-to improve the resistance of the insulator supports by adding the voltage distribution ring which is placed at the head of the column. One can increase the arc-over voltage in connection with the negative shock wave by increasing the diameter of the ring up to a certain dimension, where one no longer observes any noticeable gain. In general, however, one finds a certain diminution in the resistance to the positive wave.

One can improve the protective action of the ring for the case of the negative wave by modifying the position and one can do this by moving it from the top of the column downward; but this improvement is then obtained to the detriment of the resistance to the positive shock wave.

Now, and this is one of the characteristic features of the invention, one could keep the ring in the upper portion of the column, with a maximum effect upon the resistance to the positive wave, while still improving the resistance to the negative wave by arranging at least one intermediate ring, with a diameter smaller than that of the ring at the head. This arrangement would not reduce the resistance to the arc-over for the case of the positive wave. More generally, one could improve the resistance to the negative shock wave by retaining the diameter of the ring at the end or by keeping the positive and negative resistance voltage the same, and by decreasing the diameter of the ring at the end, adding one or more intermediate rings with a diameter smaller than that of the ring at the end, and placing these rings in certain specific positions.

Depending upon the case, one or the other operating procedure for the device involved in this invention can be given preference.

According to one characteristic feature of the invention, the arrangement of the ring at the head and one or more intermediate rings enables one to reduce the diameter of the rings with respect to the known arrangement of only one ring at the head which has a large diameter.

This invention involves all of the above-mentioned arrangements, as well as the numerical data for the relative positions of these devices or their dimensions.

In order to avoid any confusion as to the above-mentioned numerical data, one can establish the following definitions:

Ring diameter: average diameter, that is to say, diameter of the circle on which the center of the tube is located;

Tube diameter: outside diameter of tube used in making the ring;

Outside diameter of ring: sum of diameter of ring plus diameter of tube;

losition of ring: vertical distance between lower plane tangent to the ring and lower level of the mounting or mountings provided on the upper end of the support, a distance which is considered positively when the ring is arranged higher than the lower level of the mounting or mountings.

The table gives the surge arc-over voltages for the different values of numerical data pertaining to a column of support insulators for 700 kv., with a height of 4,622 mm. where the length of the last element is 880 mm., for a column of support insulators for 500 kv., with a height of 4,000 mm., where the length of the last element is 880 mm., as well as for an insulator support column for 420 kv. with a length of 3,330 mm., :where the length of the last element is 830 mm. In the table, the dimensions are given in millimeters and the voltages in kilovolts.

TABLE Ring at Intermediate Surge resistance in kv. Test Ring head tube Ring ring tube Position Column Height No. diameter diameter Position diameter diameter P1/P2 700 kv- 4,622, test element 880 1 1, 200 60 2, 364 2, 112 2 710 100 2, 426 2, 068 3 546 114 2, 420 2, 004 4 710 100 2, 374 2, 312 5 710 100 2, 430 2, 381 6 710 100 2, 363 2, 240 7 710 100 2, 393 2, 056 500 kv. 3,900, test element 780 8 1, 000 40 2, 050 2, 070 9 530 80 2, 060 1, 841 10 530 80 2, 042 1, 909 11 530 80 2, 101 1, 960 12 530 so 2, 088 2, 173

420 kv. 3,350, test element 832 13 1, 000 40 1, 700 1,840 14 450 50 0 1, 837 1, 715 15 450 50 0 400 40 50/50 1, 837 1, 715 16 450 50 0 300 40 -/150 1, 727 1, 979 17 450 50 0 300 40 0/100 1, 787 1, 847 18 450 50 0 300 40 /75 1, 775 1, 866 19 450 50 0 300 /50 1, 860 1, 691 20 450 50 0 300 40 75/25 1, 855 1, 794 21 450 50 0 300 40 100/0 1, 833 1, 969 22 450 50 0 300 40 120/ 20 l, 805 1, 836

All dimensions are in millimeters.

The figures in the attached drawing, by way of example, furnish a schematic illustration of these columns, with the arrangement and the dimensions of the upper ring and the intermediate ring or rings referring here to the optimum solution, that is to say, the solution that gives the best positive or negative surge resistance voltage.

In the drawing:

FIGURE 1 is a partial schematic, elevational view of an insulator column incorporating the present invention.

FIGURE 2 is a partial schematic, elevational view of a second embodiment of the present invention.

FIGURE 3 is a partial schematic, elevational view of yet a third embodiment of the present invention.

The drawing shows three columns composed of ceramic elements, held together by mountings. FIGURE 1 shows the entire assembly for a 700 kv. column, consisting of five elements, numbered 1, held together by mountings 2. The head element 3 is provided with a potential distribution ring 4 which is attached to upper mounting 5 in a plane perpendicular to the axis of the column.

The column in FIGURE 1, in addition, is provided :with an intermediate ring 6 which is attached to the base mounting of the head element and which is located in a plane perpendicular to the axis of the column.

The intermediate ring 6 has a diameter that is smaller than that of head ring 4.

FIGURE 2 shows a 500 kv. column consisting of five insulator elements. The head element 3 supports, in its upper portion a head ring 4 and in its lower portion it supports two intermediate rings 7 and 8, arranged on either side of base mounting 9 of the head element. The intermediate -rings 7 and 8 have the same diameter and this diameter is smaller than that of the head ring 4.

FIGURE 3 shows a 420-kv. column consisting of four insulator elements. The head element 3 supports a head ring 4 in its upper portion and an intermediate ring 6, attached beneath the intermediate mounting 11. By the table in the case of the 700 kv. column (FIGURE 1), one can replace the head ring which has a diameter of 1,200 mm., with a ring having a diameter of 710 mm., thus improving the minimum arc-over voltage for the two polarities. One can do this provided there is a ring with a diameter of 450 near the base mounting of the column head element.

The table also shows that one can replace a head ring with a diameter of 1,000 with another ring having a diameter of 530, thus improving the arc-over resistance of a 500 kv. column (FIGURE 2). One can do this provided there are two rings with a diameter of 300 mm. which are arranged symmetrically with respect to the base plane of the head element mounting. Similarly, one could replace a ring with a diameter of 1,000 for a 420 kv. column (FIGURE 3) with a ring having a diameter of 450, thus improving the arc-over resistance; one can do this, provided there is a second ring with a diameter of 300 near the base mounting of the head element.

The diameter of the rings used according to this invention is considerably smaller than that of the single ring. It is not necessary to emphasize the importance of this space gain, especially in the case where these insulator supports are intended for the construction of circuit breakers or disconnecting switches.

It is obvious that the numerical data given in these tables can vary slightly without producing any significant differences in the result. Thus, the position of the intermediate rings may vary within rather extreme limits defined by a ring situated either 50 mm. above the top edge of the intermediate mounting or 50 mm. below the lower edge of that same mounting.

On the other hand, the diameters of the intermediate rings may vary within limits of about i20%.

What is claimed is:

1. A high-voltage insulating column with improved shock Wave resistance comprising: a plurality of column elements arranged end to end and forming at the upper end thereof, a head column element, an upper potential distribution ring coupled to the upper end of the head column element, at least one lower potential distribution ring coupled to said head column element in the vicinity of its base, each of said potential distribution rings being concentrically mounted on said column and peripherally spaced therefrom, the remaining column elements being free from potential distribution rings.

2. The insulating column as claimed in claim 1 wherein the diameter of said lower ring is less than the diameter of the upper ring.

3. The insulating column as claimed in claim 2 wherein the tube diameter of the lower ring is smaller than the tube diameter of the upper ring.

4. The insulating column as claimed in claim 1 wherein the tube diameter of the lower ring is smaller than the tube diameter of the upper ring.

5. Theinsulating column as claimed in claim 1 wherein three potential distribution rings are provided and said column further includes means for attaching said second and third rings -to said column, symmetrical with the base plane of the head element.

6. The insulating column as claimed in claim 1 wherein the diameter of the lower ring is about two thirds of the diameter of the upper ring.

7. The insulating column as claimed in claim 1 wherein the axial lenth of the head element is on the order of 900 mm., said upper potential distribution ring has a tube diameter on the order of mm. and a ring diameter on the order of 710 mm., and said lower potential distribution ring has a tube diameter on the order of 40 mm. and a ring diameter on the order of 450 mm., said head element and the adjacent element thereto are coupled by a fitting which is spaced on the order of 50 mm. from said lower ring; whereby the column is adapted for operation at a voltage of 700 kv.

8. The insulating column as claimed in claim 1 wherein the axial length of the column head element is on the order of 800 mm., said upper potential distribution ring has a tube diameter on the order of 80 mm., and a ring diameter on the order of 530 mm., said lower potential distribution ring has a tube diameter on the order of 40 mm. and a ring diameter on the order of 300 mm., said head element and adjacent element thereto are coupled by a fitting which is spaced from the lower distribution ring by a distance on the order of 100 mm. whereby; the insulating column is adapted for operation at a voltage of 500 kv.

9. The insulating column as claimed in claim 1 wherein the axial length of said column head element is on the order of 830 mm., said upper potential distribution ring has a tube diameter on the order of 50 mm. and a ring diameter on the order of 450 mm. and said lower potential References Cited UNITED STATES PATENTS 1,763,170 6/1930 Miller 174-150 FOREIGN PATENTS 955,702 1/ 1957 Germany.

LARAMIE E. ASKIN, Primary Examiner US. Cl. X.R. 174-144 

